
ML66525 Family User’s Manual
Chapter 18
Media Control Function
18 - 8
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Media sequencer status register (MSSTS)
This register indicates the state of the media sequencer.
Bit 0 indicates the sequencer operation has been completed, bit 1 indicates Media Sequencer
Ready/Busy, bit 2 indicates that no ECC error was detected, bit 3 indicates that no parity error
was detected, bit 4 indicates the ready or busy state of the flash memory that has been
connected.
The bits other than bit 0 (MSCOMP) can only be read by the program. Write operations to the
bits other than bit 0 are invalid. If read, a value of “0” will always be obtained for bits 5 to 7.
When reset (RESn signal input, execution of a BRK instruction, overflow of the watchdog
timer, opcode trap), the value of MSSTS becomes 1EH.
Figure 18-10 shows the MSSTS configuration.
7
6
5
4
3
2
1
0
MSSTS
-
MRDY PRTYOK ECCOK MSRDY MSCOMP
At reset
0
1
0
Sequencer operation not completed
1
Sequencer operation completed*
0
Sequencer busy
1
Sequencer ready
0
ECC error
1
No ECC error
0
Parity error
1
No parity error
0
Flash memory busy
1
Flash memory ready
Figure 18-10
MSSTS Configuration
* Sequencer operation completed
When bit 0 (MSCOMP) is set to “1”, it indicates that the sequencer operation has been
completed and the interrupt signal to the CPU (interrupt from the internal Media contoller) has
been asserted.
Writing a “1” to bit 0 clears the interrupt, but writing a “0” does not.
[Notes]
1: The result of parity checking of the block address area when reading the redundancy
part in the SmartMedia format.
However, in SMIL (SmartMedia Interface Library) Version 1.00, a method is written
that the parity bit for the block address includes a fixed value 00010b and that even
parity for the entire block address area is to be generated.
In this case, it is necessary
to generate a parity bit by firmware and write to the redundancy part.
2: The result of ECC operation mentioned here is based on the SmartMedia specifications.
According to the ECC specifications, the situations of wrong correction, wrong
detection, or non-detection of errors can occur.
Address : 1B08[H]
R/W access : R/(W)